Sanborn Insurance Maps

by Blaine Hedberg, 2015

Do you recognize this part of Westby on the 1938 Sanborn Fire Insurance map? 

In June 1904, representatives of the Sanborn Map Company of New York visited Westby and Hillsboro to prepare fire insurance maps of these Vernon County cities. They returned to Westby in 1911 and again in 1938, and during each visit prepared detailed maps of the city businesses and homes. 

The Sanborn Fire Insurance maps, created for assessing fire insurance liability in urbanized areas of the United States, exist for approximately 13,000 locations. Daniel Sanborn, a civil engineer and surveyor, began working on fire insurance maps in 1866, preparing maps for areas of Tennessee and for Boston, Massachusetts. Seeing a lucrative market for these types of map, he established the D. A. Sanborn National Insurance Diagram Bureau in New York City to develop and sell maps. Regional offices were located in San Francisco, Chicago, and Atlanta. The Sanborn Company sent out hundreds of surveyors throughout the United States to record the building footprints and relevant details of buildings in all major urbanized areas regarding their fire liability. In the 1920s and 1930s, the company employed about 700 people, including approximately 300 field surveyors and 400 cartographers, printers, managers, salespeople, and support staff. 

 The Sanborn maps themselves are large-scale lithographed street plans at a scale of 50 feet to one inch (1:600) on 21 by 25 inches sheets of paper. Updated maps, made available to previous customers, would include drawings of new or altered buildings or lots. Sanborn maps contains an enormous amount of information, such as a decorative title page; an index of streets and addresses; an index with the names of public buildings, churches, schools, and businesses; and a master index indicating the entirety of the mapped area. General information such as population, economy and prevailing wind direction. Fire insurance maps often include outlines of each building and outbuilding; the location of windows and doors; street names; street and sidewalk widths and property boundaries. Natural features; railroad corridors; building use; house and block number; as well as the composition of building materials including the framing, flooring, and roofing materials may also be noted. The strength of the local fire department; indications of sprinkler systems; locations of fire hydrants and location of water and gas mains are generally included. With the aid of waxed paper stencils, Sunburn employees colored each map by hand. 

 An inventory of the largest collection of Sanborn fire insurance maps, found in the collection of the Library of Congress, is available through their website http://www.loc.gov/rr/geogmap/sanborn/. The archives of the Wisconsin Historical Society in Madison hold the original Sanborn Fire Insurance maps for 251 Wisconsin communities, generally dating between 1883 and 1930. It also has a complete microfilm edition of Wisconsin Sanborn Maps (in black and white). In 2014, the Wisconsin Historical Society completed a digitization project of 901 maps (7,720 page images) and lower resolution images are available through their website at http://content.wisconsinhistory.org/. The Wisconsin Historical Society can also provide high quality images from the Wisconsin Sanborn Map Collection for a small fee. Photocopies of the 1904, 1911 and 1938 Westby Sanborn fire insurance maps are available at the Westby Area Historical Society. We are indebted to David and Vanessa Mills for making these photocopies available to the Westby Area Historical Society archives.